Full Stack Lead Engineer

• Are you curious, excited by experimentation and always looking to innovate?
• Do you want to work in embedded payments where you can keep learning and developing whilst getting hands-on experience?
• Do you want to have the opportunity to play an important role in a rapidly growing and exciting Fintech business?

If so, we would love to connect and collaborate!

We want to hire ambitious, and value-adding talent into Modulr, one of the fastest growing payments businesses in the UK and Europe. Modulr is experiencing significant growth, and in this role you will work in a cross-functional team who are asked to solve a problem, rather than be handed a task to do. This is an excellent opportunity to work in a high-growth environment with a fast-paced and collaborative culture where you will have great opportunities to work on challenging problems across the entire technology stack.

About us

At Modulr our mission is to move money efficiently to power business productivity. We are building a new digital payments service to make money flow more efficiently through businesses and the economy. This is a new type of payments account that is built for businesses that need faster, easier and more reliable ways to move money.

Our flexible platform and innovative approach allows our customers to utilise our payments account instead of a traditional bank account. Our accounts come with a sort code and account number, access to payment systems (eg Faster Payments and Visa) and everything our customers need from a payments account. They can instantly open as many accounts as they need, automate how they make and receive payments as well as the reconciliation processes these create. All in real time, 24/7 through their own systems utilising our API that integrates into any platform.

Our founding team has a wealth of experience in the payments industry and growing successful businesses. Modulr is backed by payments giants PayPal Ventures and FIS Ventures, as well as startup and scale up specialists Blenheim Chalcot, General Atlantic, Frog and Highland Europe which enables us to leverage their resources and expertise to drive our growth initiatives. These partnerships provide us with the necessary provisions to propel our business to new heights.

Modulr values

• Building the extraordinary; going that extra mile.
• Owning the opportunity; be passionate and proud of the time you invest.
• Move at pace; reach goals faster whilst supported on your career journey.
• Achieve it together, working collaboratively and being a Modulite.

The Role

The Full Stack Lead Engineer is a vital role within Modulr, where you will be responsible for building an autonomous, high performing engineering squad to foster an environment where decisions are delegated, made and communicated effectively. You will drive technical strategy with a strong emphasis on Python and FastAPI backend development while remaining deeply hands-on with core development. The role is a blend of hands-on Python development, technical leadership, mentoring, and operational excellence. You will lead

the architecture and implementation of robust, scalable backend systems using FastAPI, cloud infrastructure on AWS, and coordinate full-stack solutions with frontend teams.

Specific duties

• Lead a squad of software engineers, driving technical excellence through code reviews, architectural guidance, pair programming, and mentoring with strong emphasis on Python and FastAPI best practices.
• Technically efficient to write production-quality Python code, designing high-performance REST APIs, managing databases, async operations, and establishing coding standards.
• Own backend architecture decisions and lead the design of scalable, robust systems using Python, relational databases (PostgreSQL/MySQL), caching layers, and message queues.
• Lead technical strategy for AWS cloud deployments, ensuring security, reliability, scalability, and operational excellence.
• Mentor team members to develop deep full stack expertise for both backend & frontend through 1-2-1s, code reviews, and pair programming, fostering their technical growth and career progression.
• Plan squad deliverables and delegate responsibilities clearly, ensuring the team has well-defined goals, unblocked paths to success, and regular progress tracking.
• Collaborate with Frontend, DevOps, and Product teams to deliver integrated solutions, ensuring seamless API integration between backend and frontend.
• Drive agile practices and conduct productive ceremonies (stand-ups, sprint planning, reviews, retros), promoting continuous improvement and team autonomy.
• Drive hiring and recruitment, conducting technical interviews, assessments, and candidate evaluations while representing Modulr's engineering culture and values.
• Report on squad progress, outcomes, and technical achievements to leadership; share knowledge and best practices across the broader Engineering organisation.

About you

Must Have:

• Expert-level proficiency in Python (9+ years), with deep knowledge of Python frameworks, async programming, and backend development best practices.
• Strong, hands-on experience with FastAPI, including building high-performance REST APIs, dependency injection, validation, and async operations.
• Solid experience with React and modern JavaScript/TypeScript, with understanding of full-stack integration and frontend-backend communication patterns.
• Hands-on experience designing, building and deploying systems on AWS (EC2, S3, Lambda, RDS, API Gateway, etc).
• Proven software development and technical team leadership experience, with a strong understanding of backend engineering practices and processes.
• Strong understanding of system design, microservices architecture, database design, and cloud-native application patterns.
• Experience with relational databases (PostgreSQL, MySQL) and understanding of data modeling, optimization, and migrations.
• Strong testing discipline (unit, integration, and end-to-end testing) with TDD mindset for backend systems.
• Demonstrated ability to mentor engineers and lead technical decision-making in a collaborative environment.
• Experience with Docker, Kubernetes, and container orchestration.
• Knowledge of DevOps practices, CI/CD pipelines, and Infrastructure as Code.

Good to have:

• Experience with caching solutions (Redis), message queues (RabbitMQ, Kafka), and async task processing.
• Experience in the fintech or payments domain.

Key Attributes:

• Strong problem-solver with deep analytical and critical thinking skills; ability to balance pragmatism with technical excellence.
• Excellent communication skills; ability to articulate complex technical concepts to both technical and non-technical stakeholders.
• Self-directed and proactive, with a drive to continuously learn and innovate in Python and backend technologies.
• Passionate about code quality, performance optimization, and building scalable, maintainable systems.
• Team player with strong collaborative and leadership presence, comfortable guiding the team through technical decisions.

ModInclusion

At Modulr, we are working hard to build a more positive diverse and inclusive culture that helps everyone to feel they belong and can truly bring their whole self to work. Not only is it the right thing to do for everyone in the Modulr team, it's also the right thing to do for our business, the community we operate in and attracting future talent. As part of our approach, we actively welcome applications from candidates with diverse backgrounds.